The present invention pertains to a device with which a steering power can be generated for course correction at velocities greater than zero in the case of azimuthal drive systems, e.g., poded drive or azimuth thrusters, without the drive having to be pivoted. More specifically, the present invention pertains to a ship drive unit which has an underwater housing in which an essentially horizontally arranged propeller shaft is mounted, on which propellers are arranged in front and/or in the rear. The housing is connected to the hull via a shaft having a shape favorable in terms of flow. The connection to the ship may be designed such that the shaft and the gondola and consequently also the propeller or propellers can be pivoted around an essentially vertical axis (azimuth propulsor). However, it is also possible to design this connection as a rigid connection.
Devices which permit the flow past the shaft to be affected such that a transverse force is generated on the shaft, which transverse force leads to a change in course at a forward velocity of the ship without the shaft being pivoted like a rudder, are arranged according to the present invention in the area of the shaft. This is independent of whether the drive unit of the ship is installed rigidly in the ship or whether the pivotable unit is fixed in the forward direction.
This type of course correction is advantageous in azimuthally steerable drive systems when a noise-sensitive arrangement is involved, e.g., in ships used for military purpose or ships with a high demand in terms of comfort, such as cruise ships. A pivoting movement of the drive leads to an oblique flow to the propeller or propellers in these ships, as a consequence of which the cavitation occurring as a result generates intense noise in the water and the ship. By affecting the flow in the area of the shaft, the course correction of the ship can be achieved without a pivoting movement of the drive, so that an increased sound and vibration level cannot be observed.
Similar advantages can also be seen in the case of gondola drives installed permanently in ships because the rudder necessary here can be made smaller or eliminated altogether.
In the practical application of the present invention, various devices are conceivable by means of which the flow past the shaft and consequently the course of the ship can be affected.
These devices may comprise nozzles, which are arranged at certain points of the shaft section, from which water exits, by which the flow past the shaft section is in turn changed such that steering forces are exerted on the ship. Another possibility, with a similar effect, is the drawing off of water at correspondingly selected points of the shaft.
Affecting the flow by electromagnetic effects is also conceivable.
It would also be possible to change the flow past the shaft by means of parts of a flexible design of an outer hull, so that a transverse force is generated.
An arrangement of a rotating cylinder according to the known principle of the Flettner rotor is also conceivable.